Powertrain Controls - ECM/PCM

DTC 33 Chart:

Brake Switch Circuit:

CIRCUIT DESCRIPTION
This diagnostic test functions on the assumption that a sudden decrease in non-drive (rear) wheel speed must be caused by a brake application. Non-drive wheel speed and stoplamp switch status and extended travel brake switch status are supplied to the Electronic Brake and Traction Control Module (EBTCM). If there is a 2 mph or greater decrease of non-drive wheel speed in 0.2 second and transition of the stoplamp switch contacts at the torque management brake switch or stoplamp switch without a transition of the extended travel contacts of the torque management brake switch the counter is incremented. When the counter reaches 5, DTC 33 is set. The counter will be reset to zero if a transition of the extended travel contacts of the torque management brake switch is noticed before the counter reaches 5.
The torque management brake switch contains two sets of electrical contacts and one vacuum port. The two sets of electrical contacts are normally closed and referred to as the "TCC Brake" and "Extended Travel Brake Switch" contacts. The Torque Converter Clutch (TCC) brake switch contacts provide ignition voltage to the torque converter clutch when closed (brakes not applied). When the brake pedal is depressed, the switch contacts open and the PCM opens a path to ground for the TCC electrical circuit to release the TCC.

DTC 33 WILL SET WHEN
- No DTC(s) 90, 106, 133 or 137.
- Traction control or ABS system operating normally.
- Non-drive wheel speed of 36 mph or greater. OR
- Non-drive wheel speed of 36 mph or greater and has not fallen below 1.2 mph since.
- A 2.5 mph or greater decrease in non-drive wheel speed in 0.2 second.
- Transition in the TCC contacts of the torque management brake switch or stop/BTSI/ cruise brake switch.
- No transition noticed in the extended travel contacts of torque management brake switch.
- If conditions above are true, set increment counter.
- When counter reaches 5, set DTC 33.

ACTION TAKEN (PCM WILL DEFAULT TO)
- DTC 33 does illuminate the Malfunction Indicator Lamp (MIL) (Service Engine Soon).
- Disable cruise control.
- Disable traction control.
- The PCM will substitute the status of the stop/BTSF/ cruise brake switch input for the torque management brake switch input.
- Shift adapts are maintained at current levels.
- Turn "ON" CHECK INFO CENTER telltale.

DTC 33 WILL CLEAR WHEN
The fault no longer exists and the ignition switch is cycled "OFF" and "ON."

DIAGNOSTIC AIDS
This test functions on the assumption that a sudden decrease in vehicle speed must be accompanied by a brake application. If there is a sudden decrease in vehicle speed and a transition on the extended travel brakes switch is noticed without a transition on the TCC brake switch then the TCC brake switch is considered failed.